After experienced the R8/9/10 versions, the Long Term Evolution (referred to as LTE) system has been successively and accurately studying the R11 technology. Currently, some of R8 products have gradually become commercial, while R9 and R10 are to be further product planned.
After experienced the R8 and R9 stages, based on which the R10 added many new features, such as DMRS (Demodulation Reference Signal), CSI-RS (Channel State Information Reference Signal) and other pilot characteristics, and transmission and feedback characteristics such as eight antenna support, in particular, the eICIC (enhanced Inter-Cell Interference Cancelling) technology further considers inter-cell interference cancelling technology on the basis of considering the R8/9 ICIC (Inter-Cell Interference Cancelling). The inter-cell interference cancelling technology mainly focused on the cell interference cancelling in the homogeneous network at the early stage of the R10, and the mainstream consideration was the eICIC technology and the CoMP (Coordinated Multi-point) technology. The name of CoMP suggests that multiple nodes coordinate to send data to one or more UEs (User Equipment) in the same time-frequency resource or different time-frequency resources. Such a technology can reduce inter-cell interference, improve throughput at the edge of the cell and expand the cell coverage. However, considering that the heterogeneous network has introduced more scenarios at the later stage of discussion, and the complexity of CoMP technology and time limitation of the R10 discussion finally determine that no additional CoMP standardized contents would be introduced at the R10 stage, but the demands of the CoMP part can be considered when designing the CSI-RS, so that there is no further discussion on the CoMP technology after the 60bis meeting.
The CoMP transmission mode mainly comprises JT (Joint Transmission), CS (Coordinated Scheduling)/CB (Coordinated Beamforming). For the JT, because different TPs (Transmission Points) transmit data for one UE, at this time, it needs to further study that the UE needs to generate the DMRS sequence according to the cell ID of which TP. Because the UE can generate the DMRS sequence according to the cell ID of the synchronous or serving cell in the R10 system, it does not involve in the problem of generating different sequences according to different IDs. The UE uses the cell ID to first generate a pseudo-random sequence initial value cinit that is a must for generating the DMRS sequence:cinit=(└ns/2┘+1)·(2X+1)·216+nSCID, nSCID=0 or 1  (Eq. 1)
uses the cinit to generate the pseudo-random sequence rns(m) according to the method in section 7.2 of the 3GPP LTE 36.211, and then uses the equation
                                          r            ⁡                          (              m              )                                =                                                    1                                  2                                            ⁢                              (                                  1                  -                                      2                    ·                                          c                      ⁡                                              (                                                  2                          ⁢                          m                                                )                                                                                            )                                      +                          j              ⁢                              1                                  2                                            ⁢                              (                                  1                  -                                      2                    ·                                          c                      ⁡                                              (                                                                              2                            ⁢                            m                                                    +                          1                                                )                                                                                            )                                                    ,                                  ⁢                  m          =                      {                                                                                0                    ,                    1                    ,                                                                                  ⁢                    …                    ⁢                                                                                  ,                                                                  12                        ⁢                                                  N                          RB                                                      max                            ,                            DL                                                                                              -                      1                                                                                                            normal                    ⁢                                                                                  ⁢                    cyclic                    ⁢                                                                                  ⁢                    prefix                                                                                                                    0                    ,                    1                    ,                                                                                  ⁢                    …                    ⁢                                                                                  ,                                                                  16                        ⁢                                                                                                  ⁢                                                  N                          RB                                                      max                            ,                            DL                                                                                              -                      1                                                                                                            extended                    ⁢                                                                                  ⁢                    cyclic                    ⁢                                                                                  ⁢                    prefix                                                                                                          (                  Eq          .                                          ⁢          2                )            
to generate a DMRS reference signal sequence. Wherein ns is a timeslot index in a radio frame, X=NIDcell is the cell ID, nSCID is a scrambling code identity, c(2m) is a pseudo-random sequence generated with cinit, and r(m) is the generated DMRS sequence.
For the R11, taking into account different nodes dynamically switched to different TPs or having different IDs of different cells, and considering that the R11 or R10 users switched to the TPs use the MU-MIMO (Multi User Multi-Input Multi-Output) technology to transmit data to save resources, then the DMRS sequences of the MU-MIMO users being identical can be better for different DMRS orthogonality and different users using the MMSE (Minimum mean-square error) technique to cancel the interference between the matched users, so as to achieve the accuracy of data reception and further improve the capacity of system. On the other hand, consider in the scenario of Scenario 4, since different nodes in the same Cell have the same ID (IDentity), then the UEs which are located in these nodes and configured with the TM8 (Transmission Mode 8) or the TM9 (Transmission Mode 9) can only use the nSCID to select two scrambling codes to limit the cell division gain in the Scenario 4. The latest 68 meeting proposed to use the high-layer semi-static signaling and/or physical layer dynamic signaling to inform the UE DMRS sequence to generate an ID, so as to enable the switching effect of dynamic orthogonality of interferences between one UE and other UEs and interference randomization.
For a UE with the configuration of TM9, it needs to detect two DCI (Downlink Control Information) Formats, one is DCI Format 1A and the other one is DCI Format 2C, in the PDCCH (Physical Downlink Control CHannel) or ePDCCH (Enhanced Physical Downlink Control Channel) region.
The DCI format 1A is mainly composed of the following information elements:                carrier indication field—0 or 3 bits;        Format0/Format1A discrimination bit—1 bit, the value 0 indicates the format 0, and the value 1 indicates the format 1A;        
if the Format 1A is used for the initialization of a random access process, and the CRC (Cyclic Redundancy Check) of the format 1A uses the C-RNTI (Cell Radio Network Temporary Identifier) to scramble, the remaining bit distribution is:                localized/distributed VRB (Virtual Resource Block) assignment identity—1 bit, set to ‘0’.        resource block assignment—┌ log2(NRBDL)(NRBDL+1)/2)┐ bits, all bits are set to 1        Preamble index indicator—6 bits        PRACH (Physical Random Access Channel) mask index indicator—4 bits        Remaining bits are set to 1        
Otherwise, comprising:                a localized/distributed VRB assignment identity—1 bit        resource block assignment—┌ log2(NRBDL(NRBDL+1)/2)┐ bits        
Wherein,
for the localized VRB, it is ┌ log2(NRBDL(NRBDL+1)/2)┐ bits;
for the distributed VRB:
if NRBDL<50 or if the CRC of the format 1A is scrambled by the RA-RNTI, P-RNTI or SI-RNTI, it is ┌ log2(NRBDL(NRBDL+1)/2)┐ bits;
otherwise, 1-bit MSB indicates a gap value, the value 0 indicates Ngap=Ngap,1, and the value 1 indicates Ngap=Ngap,2; (┌ log2(NRBDL(NRBDL+1)/2)┐−1) bits
Ngap is the gap between the physical resource block and the virtual resource block index when the physical resource block maps to the virtual resource block.                modulation and coding scheme—5 bits        HARQ process number—3 bits (FDD system), 4 bits (TDD system)        New data indicator—1 bit        
Wherein, if the CRC of the format 1A is scrambled by the RA-RNTI, P-RNTI or SI-RNTI, then:
if NRBDL≥50 and the localized/distributed VRB assignment identity is set to 1, the new data indicator bit indicates the value of gap, wherein the value 0 indicates Ngap=Ngap,1, and the value 1 indicates Ngap=Ngap,2.
Otherwise, the new data indicator field is reserved;
If the CRC of the format 1A is not scrambled by the RA-RNTI, P-RNTI or SI-RNTI, then: the new data indicator field is used to indicate whether it is new data or not.                Redundancy version—2 bits        PUCCH (Physical Uplink Control CHannel) TPC (Transmit Power Control) command—2 bits        
wherein, if the CRC of the format 1A is scrambled by the RA-RNTI, P-RNTI or SI-RNTI, then:
1) the MSB of the TPC command is reserved
2) the LSB of the TPC command indicates the column of the TBS table.
3) if the value of LSB is 0, then NPRB1A=2, otherwise NPRB1A=3.
If the CRC of the format 1A is not scrambled by the RA-RNTI, P-RNTI or SI-RNTI, then: the two bits of the PUCCH TPC command comprise the MSB indicator and the TPC command.                downlink assignment index (this field exists in all the uplink and downlink configurations of the TDD, and only applies to the TDD uplink and downlink configurations 1-6, and this field does not exist in the FDD)—2 bits.        SRS (Sounding Reference Signal) request field, 0 or 1 bit, and this field only appears in the DCI format which is scrambled by the C-RNTI and used to schedule the PDSCH (Physical Downlink Shared Channel) in the UE-specific search space.        
When the CRC of the format 1A is scrambled by the RA-RNTI, P-RNTI or SI-RNTI, the following fields will be reserved:                HARQ process number        downlink assignment index        
The DCI Format 2C comprises:                carrier indicator field (a UE configured with multi-carrier aggregation needs to detect this bit).        resource assignment type indicator, used to indicate the UE whether the resource assignment type used by the base station side to transmit data is the resource assignment type 0 or 1. If the downlink bandwidth is less than or equal to 10 RBs (Resource Blocks), there is no resource assignment header field.        Resource assignment bit field.        Transmit power control bit field, used for the PUCCH power control.        Downlink assignment index. This field only exists in the TDD system;        HARQ (Hybrid Adapt Retransmission Request) process indicator number.        Antenna port, scrambling code identity and the number of layers indicator field.        SRS request field.        TB (Transmission Block) information indicator field:        
TB 1:                Modulation and coding scheme indicator field        New data indicator field (NDI)        Redundancy version indicator field rvidx         
TB 2:                Modulation and coding scheme indicator field IMCS         New data indicator field (NDI)        Redundancy version indicator field rvidx         
If both transport blocks are enabled, then the TB1 is mapped to codeword 0, and the TB2 is mapped to codeword 1. If only one TB is enabled, the mapping from the TBs to the codewords is shown in Table 1.
TABLE 1mapping of transport block to codeword (single transport block is enabled).codeword 0codeword 1transport block 1transport block 2(enabled)(disabled)enableddisabledtransport—block 1disabledenabledtransport—block 2
For the single enabled codeword, the values 4, 5 and 6 in Table 2 only support retransmissions which use the 2, 3, 4 layers transmissions, corresponding to the previous codeword.
TABLE 2antenna port, scrambling code identity and layer indicator fieldSingle codeword enabledTwo codewords enabledCodeword 0 enabled,Codeword 0 enabled,Codeword 1 disabledCodeword 1 enabledValueMessageValueMessage01 layer, port 7, nSCID = 002 layers, ports 7-8, nSCID = 011 layer, port 7, nSCID = 112 layers, ports 7-8, nSCID = 121 layer, port 8, nSCID = 023 layers, ports 7-931 layer, port 8, nSCID = 134 layers, ports 7-1042 layers, ports 7-845 layers, ports 7-1153 layers, ports 7-956 layers, ports 7-1264 layers, ports 7-1067 layers, ports 7-137Reserved78 layers, ports 7-14
For single codeword one-layer transmission, when the modulation and coding scheme indicator field corresponding to the TB is IMCS=0, and the redundancy version indicator field rvidx=1, it indicates that the corresponding TB is not enabled. Then the other enabled codeword selects the transmission antenna port, scrambling code identity and layers according to the antenna indicator field. As shown in Table 2, when the indicator field Value=0, the Layer is 1 layer, the transmission antenna port is port 7, and the scrambling code identity is nSCID=0, when the indicator field Value=1, the layer is 1 layer, the port is port 7, and the scrambling code identity nSCID=1, when the indicator field Value=2, the layer is 1 layer, the port is port 8, and the scrambling code identity is nSCID=0, when the indicator field Value=3, the layer is 1 layer, the port is port 8, and the scrambling code identity nSCID=1.
For two codewords two-layer transmission, when the indicator field Value=0, the layers are two layers, the ports are ports 7-8, the scrambling code identity nSCID=0, when the indicator field Value=1, the layers are 2 layers, the ports are ports 7-8, the scrambling code identity nSCID=1, and so on, when the number of layers is greater than 2, the scrambling code identity indicates that nSCID=0 by default.